Subject: Pine Siskins
Date: Jan 11 16:03:37 1999
From: Libor Michalak - libor at atlas.geomatics.com


I too have experienced the same trend with Pine Siskins (PISI) that Eric has
here in the lower mainland of Vancouver, BC. Both my tube feeders are
sitting vacant presently. I also assume that many others have experienced
this situation.

Some information that most will find interesting is the scenario I had with
PISI while I lived in Nelson BC. A year ago I was doing some banding
studies on PISI in my backyard. Apart from eating me out of approximately
80$ worth of seed in a season, these guys came and went in waves all the
time. PISIs are known to be quite vagrantish. Just to give an example of a
banding record from Robert Yunick (personal comments) an individual have
been recovered in BC (Okanagan) that was banded a year ago in Virginia
area.

The biggest thing I noticed about this species (apart from my focus on the
species morphometrics) was the cycles that they followed. I banded
approximately 800 during my study that lasted from about November to April.
Those dates stick out in my mind because many of the individuals which
visited my feeder that year were during that time period. They seemed to
move in waves of varying numbers (20 - 100 or so for me), but the
interesting thing is that the waves were all composed of new birds. As soon
as one wave of birds came and fed for about a week they left, and another of
completely new birds moved into feast. I hardly ever saw a return on the
groups which visited the first time round. I remember about a 10-15% retrap
or something.........

Another casual observation was with the weather. Every time there was a
shift either bad to good, or good to bad it seemed that I got a new
population come and the one that was there left. Was there some kind of
intraspecific competition to explain the first leaving???? Sometimes there
were weeks where I had the feeders empty till a new wave came in following
some weather front. I also noticed, as with most birds, that their activity
prior to a bad frontal system, the birds tended to stock up on food.

I am not too sure why this sort of thing happens but it seems that the PISI
move around like e.g. the American Tree Sparrows (see Bent). I can't seem
to remember if there was a substantial change in populations, but there
certainly was a pattern coinciding to the weather.

Thats my story,
Cheers
Libor
============================================
Libor Michalak
Sr. Environmental Biologist
Geomat International Inc.
201-1600 West 6th Ave
Vancouver, BC, V6J 1R3
Phone: 604-738-5551 x225
Fax: 604-738-5529
e-mail: libor at geomatics.com
Web Site: http://www.geomatics.com/geobc/
============================================

> -----Original Message-----
> From: TWEETERS-owner at u.washington.edu
> [mailto:TWEETERS-owner at u.washington.edu]On Behalf Of StahlfeldE at aol.com
> Sent: Monday, January 11, 1999 15:23
> To: tweeters at u.washington.edu
> Subject: Pine Siskins
>
>
> Tweets,
>
> I wonder about the suggestions that feeder diseases are literally
> decimating
> siskin populations. We used to have flocks of dozens at our black-oil
> feeders, but the two previous winters had only rare single birds.
> This winter
> started out the same way, with only an occasional single bird. Then in
> November we got a huge (for us) flock of more than fifty. Delighted --
> they're more interesting than house finches -- I put out a thistle feeder
> designed especially for them (holes are below perches, house
> finches evidently
> do not feed upside down). Acrobats, they were.
>
> Then came the cold snap in December, and they vanished. Back to only an
> occasional single bird.
>
> Did they die from some disease? I really doubt it. I didn't see
> any signs of
> disease. The disappearance was instantaneous, not a gradual
> diminishing in
> number. Several other comments also suggest that the siskins disappear
> quickly.
>
> So, does anyone know whether the December cold spell chased the
> siskins away?
> The CBC's might show a trend compared to other years, but does
> anyone else get
> a feeling that siskin numbers dropped during December?
>
> For what it's worth, I am feeding with the kernels of the
> black-oil seeds, not
> the whole seed. Cuts down tremendously on the mess below the
> feeder, and if
> Jerry Converse's calculations of the relative weights of kernels
> and hulls are
> correct then it's not much more expensive. Sure lasts longer in
> the feeder.
> Only problem is keeping it dry. I gave up on the thistle,
> evidently as have
> others. Impossible to keep condensation in the tube from getting the seed
> wet, clogging the holes.
>
> Of course, nothing contained herein is intended to lessen
> potential concerns
> over feeders harming birds. With that lawyer-like disclaimer,
> ever enjoying
> the lively Tweeters discussion, I am
>
> Eric Stahlfeld
> Burien
>